JOHANNESBURG (AP) — One by one, five to a grave, the coffins are buried in the red earth of this ill-kept corner of a South African cemetery. The scrawl on the cheap wood attests to their anonymity: “Unknown B/Male.”

These men were migrants from elsewhere in Africa with next to nothing who sought a living in the thriving underground economy of Gauteng province, a name that roughly translates to “land of gold.” Instead of fortune, many found death, their bodies unnamed and unclaimed — more than 4,300 in Gauteng between 2014 and 2017 alone.

Some of their lives ended here at the Olifantsvlei cemetery, in silence, among tufts of grass growing over tiny placards that read: Pauper Block. There are coffins so tiny that they could only belong to children.

As people worldwide flee war, hunger and a lack of jobs, global migration has soared to record highs, with more than 258 million international migrants in 2017. Far less visible, however, has been the toll of this mass migration: The tens of thousands of people who die or simply disappear during their journeys, never to be seen again.

A growing number of migrants have drowned, died in deserts or fallen prey to traffickers, leaving their families to wonder what on earth happened to them. At the same time, anonymous bodies are filling cemeteries around the world, like the one in Gauteng.

Despite talk of ‘waves’ of African migrants trying to cross the Mediterranean, as many people migrate within Africa — 16 million — as leave for Europe. In all, since 2014, at least 18,400 have died or disappeared traveling within Africa, an Associated Press tally has found. The tally is based on IOM records, missing persons reports, and data from thousands of interviews with migrants conducted by the Mixed Migration Centre based in Geneva.

That includes more than 8,700 people whose traveling companions reported their disappearance on route out of the Horn of Africa.

When people vanish while migrating in Africa, it is often without a trace.

Some disappear vanish into a vast network of formal and informal prisons in Libya. And the IOM says the Sahara Desert may well have killed more migrants than the Mediterranean. But no one will ever know for sure in a region where borders are little more than lines drawn on maps, and no government is searching an expanse as large as the continental United States.

The harsh sun and swirling desert sands quickly decompose and bury bodies of migrants, so that even when they turn up, they are usually impossible to identify.

With a prosperous economy and stable government, South Africa draws more migrants than any other country in Africa. The government is a meticulous collector of fingerprints — nearly every legal resident and citizen has a file somewhere — so bodies without any records are assumed to be living and working in the country illegally. The corpses are fingerprinted when possible, but there is no regular DNA collection.

South Africa has one of the world’s highest rates of violent crime and police are more focused on solving domestic cases than identifying migrants.

“There’s logic to that, as sad as it is. ... You want to find the killer if you’re a policeman, because the killer could kill more people,” said Jeanine Vellema, the chief specialist of the province’s eight mortuaries. Migrant identification, meanwhile, is largely an issue for foreign families — and poor ones at that.

Vellema has tried to patch into the police missing persons system, to build a system of electronic mortuary records and to establish a protocol where a DNA sample is taken from every set of remains that arrive at the morgue. She sighs: “Resources.” It’s a word that comes up 10 times in a half-hour conversation.

So the bodies end up at Olifantsvlei or a cemetery like it, in unnamed graves. On a recent visit by AP, a series of open rectangles awaited the bodies of the unidentified and unclaimed. They did not wait long: a pickup truck drove up, piled with about 10 coffins. Five coffins per grave, and the space receives a marker. There were at least 180 grave markers for the anonymous dead.

The International Committee of the Red Cross and one of the Gauteng morgues have started a pilot project to take detailed photos, fingerprints, dental information and DNA samples of unidentified bodies. That information goes to a database where, in theory, the bodies can be traced.

“Every person has a right to their dignity. And to their identity,” said Stephen Fonseca, the ICRC regional forensic manager.